Techniques for cooling airfoils used in hot environments, such as the turbine section of a gas turbine engine, are continuously being developed. In extremely hot environments the airfoils are made hollow; and a cooling fluid is passed therethrough to keep the metal temperature within acceptable limits. In a gas turbine engine the air for cooling turbine stators and rotors is typically bled from the compressor flow path, routed around the burner section, and directed into the hollow airfoils of the turbine section. The cooling fluid is ejected through the trailing edge of the airfoil, and often through small holes or slots in the pressure and suction sidewalls and through the leading edge.
It is desirable to use as little cooling air as possible, since air used for cooling is air which could otherwise be used as the working fluid medium to produce thrust. Most cooling techniques try to maximize the amount of cooling accomplished by each unit mass of cooling fluid. Techniques for reducing the heat load on the airfoil itself without using cooling fluid in the process would be highly desirable and could reduce the amount of cooling fluid needed to achieve an acceptable metal temperature or could allow the airfoil to operate in a hotter environment using the same amount of cooling fluid.